'Let's be clear," Barack Obama wrote in "The Audacity of Hope" (2006). "The rich in America have little to complain about." They may have some complaints these days, along with the nonrich. David Freddoso mentions this passage from Mr. Obama's best-selling book to suggest the senator's willingness to increase taxes on the upper brackets and to spend money on government programs. But in truth it is hard to know exactly what Mr. Obama would do as president. His campaign has featured lots of post- partisan rhetoric about "change" and "reform" and, more recentlyas we heard during Friday night's debatea few standard-issue Democratic nostrums (e.g., regulation). Is he a moderate liberal or someone with a more radical agenda? How would he govern if elected?

In "The Case Against Barack Obama," David Freddoso tries to answer such questions by describing the tension between Mr. Obama's public persona and his practical politics. The key, for Mr. Freddoso, is the Chicago world in which Mr. Obama made himself first a community organizer and then a state senator (1997-2004), before heading off to Washington in 2005. It is by viewing Chicago that the gap between Mr. Obama's rhetoric about reform and his career as a conventional Chicago pol is most visible.

In the past week or so, we have learned more about Alaska than we ever cared to know, including details about tiny Wasilla, where Sarah Palin once served as mayor. But about Mr. Obama's hometown we hear very little. Chicago, let it be said, is a place in decline. In recent yearsand well before the current economic turmoilit has lost its two leading banks and thousands of jobs in the futures and commodities markets. Not only does it have the highest retail sales tax in the country, at 10.25%, it is the only city with a head tax on employment. Its public schools are in terrible shape. The city's middle-class population continues to flee. (Chicago lost 63,000 people between 2000 and 2006.) Meanwhile corruption and crime, not to mention machine politics, continue to thrive. In Chicago, it is no big deal to discover that an alderwoman's boyfriend is a member of the Gangster Disciples; this was the same gang that was given voter-registration money by Mayor Richard M. Daley. Chicago's murder rate is three times that of New York.

If there were ever a place in need of "change" and "reform," it is Chicago. And yet, Mr. Freddoso argues, reform for Mr. Obama "is something to discuss during election campaigns, not to be implemented or followed" when it might jeopardize his ambitions. Mr. Freddoso can't find a single example of a cause on which Mr. Obama has risked his political capital. This fact, Mr. Freddoso notes, "does not separate him from most other politicians in either party." It simply means that he is "like most of the others."

Is murder out of control? Are the Chicago schools failing minority children? Is the local economy faltering? These have not been Mr. Obama's concerns. He has been a down-the-line Chicago pol on such mattersdecrying police misconduct, calling for yet higher teacher salaries, and urging new subsidies for the state's industries, such as ethanol and coal. As a state senator, he routinely backed earmarks to reward potential allies. Emile Jones, the president of the Illinois state senate, pushed along Mr. Obama's rise by giving him meaningless ethics bills to shepherd through final approval after other people had done the hard work.

If there is nothing terribly shocking in any of this, it does dull the glow of Mr. Obama's halo; and some of his dodgier Chicago affiliations may remove it. In 1986, Mr. Obama's political mentor, state Sen. Alice Palmer, returned from attending the 27th Congress of the Communist Party of the Soviet Union optimistic about the U.S.S.R.'s future. A decade later she brought Mr. Obamaalready a member of the Rev. Jeremiah Wright's black-nationalist churchtogether with 1960s terrorist Bill Ayers, who would hold the first fund-raiser for Mr. Obama when he was running to fill Ms. Palmer's state-senate seat. Mr. Obama and Mr. Ayers worked together on the boards of two foundations.

Mr. Freddoso is rightly reluctant to accuse Mr. Obama of sharing the extremist views of those who helped to make his political career possible. Indeed, Mr. Freddoso is at something of a loss to explain why Mr. Obama would affiliate himself with such people. But perhaps it is not such a mystery after all. By his own admission, Mr. Obama's eyes were long on the prize of becoming the mayor of Chicago. Thus his willingness to make common cause with Tony Rezko, Allison Davis and Valerie Jarrett, locally wired political figures who did well for themselves by using state dollars to build publicly subsidized slums. In the context of Chicago's mix of black-nationalist, gentry-liberal, machine- and mob-connected politics, what Mr. Obama did was unexceptional. He simply cultivated the people he needed to cultivate in order to climb the greasy pole of local preferment, giving beautiful speeches along the way.

When in 1948 Jake Arvey, the Chicago political boss, was asked why he had chosen the patrician Adlai Stevenson to run for governor, he replied that he needed to perfume the ticket. For various Illinois politicians and machine operatives, Mr. Obama seems to have served a similar purposeeven as he served his own ambitions. A man so drawn by his own star is likely, if elected, to throw over old allies (think of the Rev. Wright) in pursuit of new goals. The only thing we can be certain of, when it comes to an Obama presidency, is that a great deal of money will be shoveled into Chicago.